When I was using Geant4 V11.2.2, the following information appeared when running the program. However, such a problem did not occur in Geant4 v11.2.1 and v11.0.3. I suspect that it was caused by the code changes of the newly added model in v11.2.2. But how to solve it?
NeutronHP: /Capture file for Z = 18, A = 36 is not found and NeutronHP will use /home/esword/.local/software/geant4/11.2.2/share/Geant4/data/G4NDL4.7.1/Capture/CrossSection/18_37_Argon
NeutronHP: /Elastic file for Z = 18, A = 36 is not found and NeutronHP will use /home/esword/.local/software/geant4/11.2.2/share/Geant4/data/G4NDL4.7.1/Elastic/CrossSection/18_37_Argon
NeutronHP: /Inelastic file for Z = 18, A = 36 is not found and NeutronHP will use /home/esword/.local/software/geant4/11.2.2/share/Geant4/data/G4NDL4.7.1/Inelastic/CrossSection/18_37_Argon
NeutronHP: /Capture file for Z = 18, A = 38 is not found and NeutronHP will use /home/esword/.local/software/geant4/11.2.2/share/Geant4/data/G4NDL4.7.1/Capture/CrossSection/18_39_Argon
NeutronHP: /Elastic file for Z = 18, A = 38 is not found and NeutronHP will use /home/esword/.local/software/geant4/11.2.2/share/Geant4/data/G4NDL4.7.1/Elastic/CrossSection/18_39_Argon
NeutronHP: /Inelastic file for Z = 18, A = 38 is not found and NeutronHP will use /home/esword/.local/software/geant4/11.2.2/share/Geant4/data/G4NDL4.7.1/Inelastic/CrossSection/18_39_Argon
models/particle_hp:
o G4CrossSectionHP: …
Fixed elastic and capture cross-sections in Argon, by using only the main
isotope Z=18, A=40 (there was up to 50% overestimation of cross-sections
due to wrong data for rare isotopes of argon).
and
Data
----
+ G4NDL-4.7.1:
o Removed all files for Argon-36 and Argon-38 as significantly different
from those of ENDF/B-VIII.0.
Of course, if you have no argon in your simulation, then it makes no difference at all. If you have air in your geometry, elemental argon comprises only 0.934% of the gases in air and Ar-40 is 99.6 % of the elemental argon (Ar-36 is 0.334%, Ar-38 is 0.063%). So it will make a very small, likely negligible, difference.
If you have a pure natural or single isotope argon target, it will make a difference but I am unsure how much. The release notes suggest it will improve estimates, but the developers might want to jump in with a more quantitative answer.
I think @John_McFee gave already the answer, here it is the plots with the cross sections for argon. I think the original error happened in the data evaluation, and then propagated to Geant4.
I will open a bugzilla ticket regarding the error message.
Hello all, I’m just starting to use version 11.3 which includes the argon fix. However for estimation of backgrounds from neutron capture on argon, Ar-36 isotope is important, since it gives a gamma cascade of ~9 MeV which is higher than the ~6 MeV. Then the question is, how to keep the Ar-36, but adjust the cross section? any suggestion is welcome. BTW why the fix consist in removing Ar-36 instead of fixing the cross section?
Best,
Luis
Thanks for the feedback @atolosad !
If I understand correctly better to avoid JEFF-3.3 ? I’m trying ENDF/B-VIII.0 and now I have again neutron captures on Ar-36.
I saw that in version 11.3 we can choose NUDEX for the gamma cascades. In addition to adding:
auto param = G4HadronicParameters::Instance();
param->SetEnableNUDEX(true);
do we need to do something else? I’m not sure if it’s taking it into account.
thanks again!
Luis
In case someone end here searching nudex info.
It seems that for now it only works with QGSP_BERT_HP physics list.
And you need to download the G4NUDEXLIB library.
I think @John_McFee this might be interesting for you. Gamma cascade for n capture in argon with nudex is nicely reproduced!
Best,
Luis
I’m not so sure about the idea of “better avoid JEFF-3.3.” Each data library selects its content based on different criteria, some prioritize experimental data, others rely more on theory. If I remember correctly, JEFF might actually perform better in some high-energy physics cases, but someone with more experience might want to jump in here.
As far as I know, there’s no issue with creating your own physics list using NUDEX instead of sticking with the built-in QGSP_BERT_HP [1].
Also, do you happen to know if the 36Ar data in JEFF and ENDF/B is purely theoretical? If so, that could explain why it appears in RIPL (via NUDEX) but not in JEFF.